The Axial Offset Anomaly (AOA) is a major impediment to increases in reactor fuel performance preventing PWRs from operating with even more efficient core designs than they are at present. It is a phenomenon where boron compounds such as lithium-metaborate and nickel-boroferrite concentrate and precipitate during reactor operation in corrosion products deposited on high-duty fuel assemblies at subcooled nucleate boiling conditions and cause the reactor neutron flux and core axial power distribution to deviate from the predicted distribution. The purpose of the present work is to describe the fundamentals in CRUD formation, transport, and deposition, in order to provide a theoretical basis for evaluating and analysing any fuel operational problem due to CRUD deposits. A Lattice Boltzmann Method model is proposed for simulating thermal hydraulic and chemical conditions in the coolant and the formation process of the CRUD.